A main engine oil gallery may be provided in an engine to supply engine components such as a camshaft and crankshaft with lubricating oil. In order to reduce oil viscosity and thus lower the energy required to pump the oil, engines may be provided with systems to heat the oil. For example, an external heater may be provided to heat the oil in the oil gallery. However, the external heater itself requires energy to function and therefore contributes to overall fuel usage in the engine, lowering fuel economy. In other concepts, the engine oil which is heated during operation is stored in an insulated container and utilized on demand, for example in the event of a re-start of the internal combustion engine. A disadvantage of this approach is that the oil which is heated during operation cannot be kept at a high temperature indefinitely, and it is therefore generally necessary to heat the oil during the operation of the internal combustion engine. Additionally, both an external heating device and also an insulated container result in an additional installation space requirement in the engine bay, and are detrimental to the attainment of the densest possible packaging of the drive unit.
Further, engine combustion cylinders may be provided with mechanisms to dissipate excess heat produced during combustion. However, the cooling may not extract more heat from the internal combustion engine than is absolutely necessary, because the extraction of heat or the extracted amount of heat has an influence on the efficiency of the internal combustion engine. In some engines, more than one quarter of the energy used is dissipated to the coolant, that is to say generally to the cooling water, of the liquid cooling arrangement and is dissipated, unused, to the environment.
The inventors herein have recognized the above mentioned issues and have developed a solution to at least partly address them. Accordingly, an internal combustion engine is provided. The engine comprises at least one cylinder, each cylinder having an outlet opening on an outlet side for discharging exhaust gases and an inlet opening on an inlet side for receiving fresh air, at least one cylinder head, and a liquid cooling device comprising at least two coolant jackets integrated in the cylinder head, wherein at least one coolant jacket is arranged on the inlet side of the at least one cylinder and at least one coolant jacket is arranged on the outlet side of the at least one cylinder, the at least two coolant jackets being separate from one another and belonging to different coolant circuits.
For example, the coolant jacket arranged on the inlet side may belong to an oil coolant circuit while the coolant jacket arranged on the outlet side may belong to a water coolant circuit. In this manner, engine oil may be rapidly heated via heat transfer through the inlet side coolant circuit. Additionally, as water has a higher heat capacity than oil, the water coolant circuit may be able to provide a higher level of cooling to the outlet side of the cylinder than the oil coolant circuit provides to the inlet side of the cylinder. Because the inlet side of the cylinder may not release as much as heat as the outlet side, an appropriate amount of cooling can be tailored to each cylinder side, reducing excess cooling and conserving energy.
The above advantages and other advantages, and features of the present description will be readily apparent from the following Detailed Description when taken alone or in connection with the accompanying drawings.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.